[Sean H]

Came last night and have been addicted to it since I fired it up. Beautiful, solidly built little thing. It's about the same size as my Perreaux SHX-1 headamp. For those of you not familiar with this DAC it's making huge waves, especially in the Audiogon, Audo Circles and Audio Asylum discussions. It's a very simple battery powered DAC that is based on a filterless, no-oversampling design. Here's a snippet from Ack!:

The battery-based power supply provides the foundation for dAck!'s unique sound. The transformer, rectifier, and filtering circuits present in most digital to analog converters contribute to a gritty, shrill, and unrestrained sound – something digital sources cannot afford if the end goal is to convey music. Three Linear Technologies precision regulators are used to further eradicate noise in already ultra-quiet battery supplies. Oversized supply capacitors are highly regarded Panasonic FC series incorporating ample bypassing by high quality film parts. Proper grounding – extremely important for any digital system – is accomplished on the high quality PCB with oversized traces routed for noise prevention and isolation from stray currents.

The sound is extremely unique. Or is it? You might at first think it sounds a bit rolled or gentle but it becomes clear the DAC is absolutely free from noise and has a scary jet black background. Ack! claims the sound is very analog or vinyl-like and I have to completely agree. There is a complete lack of glare in the treble range and that slightly hashy, or harsh laden quality that can rear it's head in even the best digital is seemingly absent. Bass is all there, midrange is absolutely perfect in every way, the treble is unbelievably coherent and clean. You can't help but get the feeling you are hearing unrecorded music, free from electronics and hi-fi. Dynamic too? Yes! Very dynamic and excellent pace as well. Resolution is top shelf as is spatial qualities. So far I am extremely impressed. The thing sounds incredible.

I was about to get on Chris Own's (Ack! Industries) waiting list which is 6-8 weeks but found this one used and had to snag it. Chris had been selling these for $395 new but Chris has revised it a hair and with demand has had to increase the price a bit to $525 shipped. Still not bad considering many say this is the finest DAC they have heard regardless of price and others say it easily competes with DAC's well into thousands.

More impressions to come.

Here's a link to Ack!:

http://ack.dhs.org/

 

[Musicfan123]

If this DAC is so perfect, why are people selling them?

 

[Sean H]

Hi Musicfan123- It seems like no matter how good anything is in our hobby people have to move on to other things!

Nothing is good enough for most of us psychos. I haven't seen many of these for sale, only a couple recently and only a couple others since they came out last summer. All that said I could see how someone might actually prefer a more agressive, edgy sound and find the dAck! simply too pure and analog-like for their tastes. Also, you have to consider the battery power thing an issue too. Or, however much of an issue you want to make of it. To maintain good cell life it's suggested the dAck! only be played for about 4 hours max (some say a little more is fine) and then a quick ~30 minute or so charge is in order and then you are good to go again. That might not be for everyone.

 

[kuma]

congrats Sean!

So, you've discovered the goodness of non upsampling/filtering.

How does it fair compared to highly touted ART DAC?

BTW, which transport are you using?
I found, for 47Lab's Shigaraki for instance, extremely sensitive to the sound of transport in use.

 

[lan]

What kind of batteries does thing use?

 

[Sean H]

Quote:

Originally posted by kuma congrats Sean! So, you've discovered the goodness of non upsampling/filtering. How does it fair compared to highly touted ART DAC? BTW, which transport are you using? I found, for 47Lab's Shigaraki for instance, extremely sensitive to the sound of transport in use.

Hi Kuma- Well, it's been a while and many sources since I owned the Art but from what I remember it sounded very different from the dAck! I just got through reading Carlos3's "The Valved CD3000" review in the headphone section (very nice review) and in it he mentioned the sound of the Scott Nixion filterless tube DAC whihc is supposed to share very similar qualities to the dAck! It's hard to compare the dAck! to something like the Art because frankly I think it just sounds so much better. If you've heard the Art and the 47 Labs do you think they can be easily compared? Tweaked out Art DI/O's can sound pretty darn good but the dAck!, and likely all of the these similar designs (Scott Nixon, 47 Labs), simply are unbelievable.

What transport am I using? What's a transport? Ha!

As much as this will make you cringe, I am using my Mac and a M-audio Revolution card's coaxial digital output as my transport. I'm using a good Belden 1695a digital cable I made. Sounds fantastic to me. I tend to listen t so much 128k streaming audio stations in iTunes and Shoutcast along with my CD's that a computer/transport solution works out great for me. I am sure a dedicated transport would maximize the dAck! potential but I'm pretty darn happy right now. Chris claims the dAck! isn't as sensitive to transports as some other similar designs but can't remember his exact explanation. I think it's on his web site??

Pretty darn amazing how good these designs can sound, as you know with the 47 Labs. Extremely analog-like. Very impressed so far.

 

[Sean H]

Quote:

Originally posted by lan What kind of batteries does thing use?

Hey lan- Chris tells me they are "a pair of sealed lead acid batteries." I'm not familiar myself. Pretty darn cool though, when not using the DAC you just shut it off and it immediately starts to recharge. It may take a good 8 hours of continuous play to fully drain the batteries but it's not recommended to do that instead he recommends 4 hours of continuous play and then a quick 30 minute recharge to full. It's easier on the cells rather than pulling them back from a deep recharge, which extends life.

 

[Iron_Dreamer]

Be honest now, you bought it just so you could say "I'm the sack who listens to FLAC on an ACK! DACK!", now didn'tcha?

 

[MirandaX]

Interesting comments, Sean. I've been thinking of building a similar type of DAC myself for some time (based on Andreas' Ciuffoli's design, with upsampling mods). There's definitely something smoother about designs that don't have an active analog filter. Digital filterless designs I'm not as sure about -- it probably depends on the specific DAC IC.

The current price of the ACK unit seems pretty reasonable too; one of the things that's been holding me off from building a Ciuffoli's DAC is that the Lundahl transformers are so expensive.

 

[Sean H]

Quote:

Originally posted by Iron_Dreamer Be honest now, you bought it just so you could say "I'm the sack who listens to FLAC on an ACK! DACK!", now didn'tcha?

LOL!

It's one crazy name.

 

[Sean H]

Quote:

Originally posted by MirandaX The current price of the ACK unit seems pretty reasonable too; one of the things that's been holding me off from building a Ciuffoli's DAC is that the Lundahl transformers are so expensive.

Yeah, I gotta tell you, I'm not experienced enough to fully understand every facet of these designs but understand the fundementals. The Ack! web site talks a bit about it. Scott Nixon's DAC's look darn intriguing too. The dAck! is definitely reasonably priced, no dout there, and after hearing it I find it a phenominal value.

 

[Iron_Dreamer]

I just read through their website, and the DACK sounds very well-thought out, as if to make one think "why don't they design them all like this?" I don't know if I could handle the limited use period as governed by the battery capacity though.

 

[kuma]

Quote:

Originally posted by Sean H If you've heard the Art and the 47 Labs do you think they can be easily compared? Tweaked out Art DI/O's can sound pretty darn good but the dAck!, and likely all of the these similar designs (Scott Nixon, 47 Labs), simply are unbelievable.

Sean,

I haven't heard ART thingy in my rig. but, I still have Bel Canto DAC 2 along with Shigaraki DAC. Indeed they are different and very difficult to qulify which one is *better* per se.
In my speaker system, Shigaraki works better than Bel Canto DAC2 whilst, with Grado RS1, I still prefer DAC2 over Shigaraki.
I've heard the proto type version of Ack DAC in the same system and Shigaraki is my second non filterless design based DAC. I am sure there are variations based on the same cct. design.

Quote:

What transport am I using? What's a transport? Ha! As much as this will make you cringe, I am using my Mac and a M-audio Revolution card's coaxial digital output as my transport.

Ha! me too! Main reason I had to look for a DAC is that for the office setup, most of the time, I access tunes stored in external Hard drives via this lap top. ( iTunes ). It's a better way of sending info to a DAC than using a separate transports, imho. Altho, I wish I could do away with a use of USB and adaptor.

I've tried number of transports i had in the house to see what kind of effects they have on a DAC. In fact, Shigaraki does very well on uncompressed files or mp3 via Wilson. It seems a transient responce is better preserved over Bel Canto and Shigaraki adds a nice organic natural feel to the music along with excellent bass dynamics and decay much like a good analogue playback.
DAC being sensitive to transports used is jitter related. But, I really don't care why that is. I just found this fascinating.

Bel Canto DAC2 sounds like a hifi prima donna next to both Shigaraki and Ack! Dac via Wilson.
I still continue to use DAC2 with RS1, however. Different transducer all together.

I did not pursue Ack! Dac further since I couldn't deal with recharging battery.

At any rate,non-upsampling design does offer something different from popular upsampling DACs. Incidentaly, two of my favorite cd players Linn Ikemi and Naim CDX2 do not upsample either. What I can see the similarity in all non sampling units I tried is that they all exhibit excellent timing properties whereas upsampling designs do well in atmosphere and depth rendition.

I am curious to see your experience with Ack! over a long run.

 

[Sean H]

Kuma- Ah, so you have heard the dAck! Cool. It's intruiging to know you liked it given the plethora of top shelf sources you have or have owned. I'm curious how the dAck! prototype compared to the Shigaraki? Had Chris improved the dAck! after you heard it?

So you are using your Mac too!

What USB adapter are you using? I had been using a Sonica via USB and then sending it's toslink output to my Cal Sigma tube DAC via one of those ebay glass toslink cables. I recently picked up an M-audio revolution PCI card and find it's coaxial output to be a hair better than the Sonica/glass Toslink connection. Very close but the Revo/coaxial connection is better through the midrange and treble, but the bass of the Toslink/Sonica was a bit better. With the dAck! I have no choice but to use the coaxial connection now. I guess if you are using a laptop the Revolution card is not an option.

It's looking like I may be parting with my Cal DAC (not sure yet) which will be hard because that DAC is a fantstic DAC as well.

Very interesting your comments about the Shigaraki and DAC2 with your Wilsons and RS-1. Interesting too when you said you could see the similarity in all non-sampling units you tried that they all exhibit excellent timing properties whereas upsampling designs do well in atmosphere and depth rendition. I definitely agree the dAck! is great with pace and timing. As to depth I'm hearing good depth and atmosphere via HD650's but do know what you are saying about atmosphere. There is air and atmosphere but compared to my Cal DAC and memory of other DAC's there is that real high end treble air and decay somewhat slightly absent but I have been wondering if that was artificial, maybe an artifact of electronics or even power related. Maybe, maybe not, but an interesting question.

As to the battery thing it's not a big thing with me really as I will use it in my home rig and tend to listen for only a couple hours an evening right before bed. You can push it up to 8 hours Chris says but to preserve life of the batteries he suggests shorter durations. Recharge time is very quick, that's good. It will be interesting to see how the dAck! sits with me over time. So far it's a good fit for my tastes and my system.

 

[fewtch]

I've heard that DACs with no filtering (digital or analog) put out a lot of ultrasonic noise over 21 KHz... inaudible, but can be dangerous to stuff like ribbon tweeters. Just a cautionary statement to anyone who's considering buying one, probably worth consulting with the designer if you have equipment that may be susceptible.

Edit... FYI after poking around the web:

http://home.triad.rr.com/scottnixon/dac.htm

http://www.geocities.com/rjm003.geo/...o/diy_dac.html

http://home.student.utwente.nl/f.s.b...dio/nonoz.html

"The downside of non-oversampling is that still some high frequency signals will go the amplifier and speakers. In the amplifier, this can cause intermodulation. Quick amplifiers with a high bandwidth (100 KHz or so) are therefore recommended. The tweeter of the speakers has to work harder due to the extra HF signals. In most cases, this is not a big problem. Watch out with ribbon tweeters or low power tweeters!"